Opposed vortex combustion chamber

ABSTRACT

A combustion chamber for burning fuel oil or the like consists of a tubular housing wherein a source of air is introduced axially along the interior walls of the chamber, the air being directed by baffles inwardly in two streams which flow in opposite circumferential directions. The counter rotating vortices intersect each other within the chamber. Fuel is introduced at some point along or near the dividing line of the vortices for uniform fuel-air mixing thereby enhancing the combustion properties of the mixture.

United States Patent Velie et a1.

[451 Jan. 25, 1972 [54] OPPOSED VORTEX COMBUSTION CHAMBER [72]Inventors: Wallace W. Velie, Woodland Hills; Robert D. Scherer, NorthHollywood, both of Calif.

[73] Assignee: North American Rockwell Corporation [22] Filed: Dec. 29,1969 211 Appl. No.: 888,243

[52] US. Cl ..43l/35l, 431/265 [51] Int. Cl ..F23d 15/00 [58] Field ofSearch ..43 l/265, 351, 352

[56] References Cited UNITED STATES PATENTS Logan 2,516,063 7/1950 Loganet a1. ..431/265 2,930,194 3/1960 Perkins ...431/352 X 3,306,334

2/1967 Goubsky ..43l/352 X Primary Examiner-Carroll B. Dority, Jr.Attorney-L. Lee Humphries and Thomas S. MacDonald 57 ABSTRACT Acombustion chamber for burning fuel oil or the like consists of atubular housing wherein a source of air is introduced axially along theinterior walls of the chamber, the air being directed by bafflesinwardly in two streams which flow in opposite circumferentialdirections. The counter rotating vortices intersect each other withinthe chamber. Fuel is introduced at some point along or near the dividingline of the vortices for uniform fuel-air mixing thereby enhancing thecombustion properties of the mixture.

ii Claims, 4 Drawing Figures PATENTEU JRN25I972 WALLACE W. VEL/E ROBERTD. SCHEREF? BACKGROUND OF THE INVENTION Conventional fuel furnaces usedin, for example a domestic environment, use some mechanism of fuel-airmixing for efficient combustion within the burner or combustion chamber.A number of fuel-air mixing designs are known in the prior art. Mostfuel oil burners utilize a single circumferential vortex generator toinduce fuel-air mixing. However, when utilizing the foregoing mechanism,the-air mass accumulates at the periphery of the burner head while fuelis introduced near the center, consequently a large mass of air isrequired to provide enough oxygen for proper burning. A good indicationof how well the fuel-air mixture is consumed or burned is the residuefrom the combustion process, i.e., the smoke and soot generatedtherefrom. Obviously, the more desirable process would be the processwhich produces the least amount of smoke or soot which means, inessence, all of the fuel injected into the combustion chamber isconsumed.

Conventional state of the art fuel burners generate a certain amount ofsmoke and soot largely due to relatively poor combustion of the fuelresulting from a nonuniform mixture of air and fuel.

Therefore, it is an object of this invention to provide a fuel oilburner which provides a uniform mixture of fuel and air.

More specifically, it is an object of this invention to provide a fueloil burner which includes a secondary source of air introduced into thecombustion chamber in oppositely rotating vortices which converge orimpinge at a point the introduction of a primary fuel-air mass therebyencouraging a uniform mixture of the fuel oil with the air prior toignition for more complete combustion of the atomized liquid.

SUMMARY OF THE INVENTION Briefly, in accordance with one form of theinvention, an improved fuel combustor is proposed wherein more completemixing of the air and the fuel is provided whereupon when ignitionoccurs, the mixture is completely consumed thereby producing virtuallyno residue, i.e., smoke and soot.

The combustion chamber consists basically of a tubular section having atone end, a burner element or atomizer whereby the fuel is injected by aprimary source of air into the chamber downstream of the burner assemblywhile at the same time introducing a secondary source of air axiallyalong the interior wall of the tubular chamber.

The burner element or fuel atomizing device may be that shown in US.Pat. No. 3,425,058 which is subsequently briefly described relative toFIG. 1 of the present invention. The atomizer disperses the fuel in avery fine uniform droplet size, in a relatively narrow cone." In orderto provide a uniform mixture of air and fuel droplets, an effectivemeans is needed to disperse the cone produced by the atomizer. Aneffective means to penetrate the cone" for uniform mixing is a bafilewhich is partially concentric with the combustion chamber being spacedfrom the interior wall of the chamber thereby fonning an annulus fordirecting the secondary source of air. A radially outwardly extendingend plate at the downstream end of the baffle closes off the spacedefined by the baffle and the interior wall of the tubular sectiondownstream of the atomizer element. A secondary source of air isintroduced between the baffle and the inner wall of the combustionchamber so that the air axially traverses the wall of the chamber,strikes the end plate of the bafile and enters the combustion chamberfrom both open sides of the baffle tangentially thereby creating a pairof counterrotating air masses. The counterrotating vortices f thesecondary mass of air impinge or intersect the cone" of finely atomizeddroplets of fuel emanating from the fuel atomizer thereby uniformallymixing the fluid for ignition. A radially oriented slot near the closedend of the baffle downstream of the counterrotating air masses isprovided to cause a jet or fan of air radially across the end of thecombustion zone to create a kind of barrier or pneumatic restriction topartially confine the turbulent air masses thereby further ensuring auniform combustion of the mixture of air and fuel; A conventional sourceof ignition such as arcing electrodes subsequently ignites thethoroughly mixed fluids.

An advantage over the prior art is the concentration of at least a pairof longitudinally extending counterrotating masses ofair near the coneof injected atomized liquid in the chamber thus ensuring the propermixture of air and the fuel oil resulting in a completely combustedproduct which more economically consumes the fuel.

DESCRIPTION OF THE DRAWINGS The above noted objects and furtheradvantages of the present invention will be more fully understood uponthe study of the following detailed description in conjunction with thedetailed drawings in which:

FIG. 1 is a partially cutaway perspective view of the preferredembodiment of the invention including all of the essential elementsthereof;

FIG. 2 is a section taken along lines 2-2 of FIG. 1 illustrating theentrance channel of the secondary source of air;

FIG. 3 is a semischematic view of the two vortices formed by the bafflestructure of the preferred embodiment, and,

FIG. 4 is another embodiment shown schematically of a combination ofvortices and battles within a burner assembly.

Referring now to FIG. 1, a tubular or gun burner assembly or combustionchamber generally designated as 10 is mounted within a conventionalfurnace (not shown) at end plate 12. The combustion chamber 10 consistsof a tubular housing 11 having therein, a radially extending plate 14which acts which acts as a basic mounting bulkhead for the fuelatomizing assembly 16, igniter assembly 18 and the concentric baffle assembly generally designated as 20.

The fuel atomizing assembly briefly described, admits liquid, forexample fuel oil, through conduit 22 which gravitationally flows overthe sphere 24. The overflow liquid is collected in the bottom of housing26 and is recirculated back to the liquid supply source (not shown)through conduit 28. A primary source of air under higher than ambientpressure (not shown) is introduced through conduit 30 which exitsthrough slot 32 in sphere 24. The resultant passage of air through theslot atomizes the liquid which is stretched over the end of sphere 24ejecting the mixture in a finely atomized narrow cone" of droplets(previously described) within a combustion zone 40 downstream of theaperture in support wall or bulkhead 14. The finely atomized mixture ofthe fuel oil or the like is then ignited by ignition source 18.

The baffle assembly 20 primarily functions to enhance the combustionproperties of the atomized liquid after it is injected through apparatus16. Baffle assembly 20 consists of a semicircular plate 42 and is fixedat its base 44 to bulkhead 14. The downstream end of the plate 42 isclosed ofl by a radially outwardly extending end plate or skirt 46 whichis attached to the interior wall of the housing 11 thereby closing offthe annular space between the baffle plate assembly 20 and the interiorof the housing 11. Preferably, as shown, the end plate is curved so asto enhance smoother flow and direct the flow in the annulus formedbetween the baffle and housing wall. The baffle assembly 20 defines atleast a pair of axially extending openings or slots 48 and 50 therebypennitting a secondary source of air (not shown) to flow tangentiallyfrom both of these openings.

The opposed tangential entry of secondary air in a direction transverseto the axis of the tubular chamber out of each opening 48 and 50 of thebaffle .20 performs two functions. First, the air directed along thecurved wall of the chamber cools the chamber walls providing a bufferzone keeping the heat away from the walls and secondly, the opposingforce of the two streams being directed by the curved wall meet oppositethe baffle creating a pair of longitudinally extending counterrotatingvortices which effectively and uniformally mix the relatively narrowcone" of droplets emanating from the atomizer when the atomizing elementis located adjacent the intersecting line of the two vortices.

Referring to FIG. 2, an entrance opening 52 in plate 14 is shown for theintroduction of a secondary source of air. The air enters throughopening 52 into the annular space defined by the bafile assembly 20 andthe interior of housing 11. The air enters axially, some flows throughslots 48 and 50, the remainder strikes end closure plate 46 and escapesthrough radial opening(s) 60 or is recirculated. The tangentiallydirected secondary air mass escaping through openings 48 and 50 inopposite directions creates a pair of vortices which meet in combustionzone 40. The converging counterrotating vortices impinges with theatomized cone of liquid ejected through assembly 16 lengthwise thereofthereby further mixing the combustible mass. After the igniter device 18is activated, a more complete combustion of the atomized liquid isinsured resulting in a relatively smokeless combustion of the fuel. Tofurther encourage mixing of the fuel and air, a radially extending slot60 located near the end closure plate 46 of the assembly 20, emits a fanof air radially inwardly extending across the end of the combustion zonedesignated as 40. A pneumatic restriction of the turbulent airflow isprovided thereby partially confining the mass within the combustion zoneof the burner assembly 10. V

The bafile device 20 including the radial slot 60 so directs andconfines the secondary flow of air entering through opening 52 and outthrough slots 48 and 50, (as clearly shown in FIG. 3) to more thoroughlymix the primary atomized fuel-air mass for complete combustion. Thebaffle assembly 20 is designed with restricted openings 48 and 50accelerate the air masses tangentially out of these openings creating ahighly turbulent pair of oppositely rotating vortices which initiallycools the wall of the chamber and meet adjacent the atomized liquidejected from assembly 16.

The schematic diagram of FIG. 4 is illustrative of another embodiment ofthe invention wherein there are two atomizing assemblies 70 and 72 eachof which are supplied with a primary source of air for initialatomization of the liquid. At least a pair of bafile assembles 74 and 76are included to produce a total of four counterrotating vortices ofsecondary air at or near the impingement point of the liquid air mixtureemanating from all of the atomizing apparatuses as heretofore described.Again radial slots 80 and 82 may be provided to pneumatically partiallyclose off i the combustion zone downstream of the combustible mass toconfine the turbulent mixture.

Any number of primary atomizing devices could be used with acorresponding number of baffle assemblies to create multiple vorticeswhich converge along the longitudinal axis of the fuel-air mixturethereby ensuring complete mixing of the combustible product. Therefore,there is a variety of combinations that could be employed whileremaining within the boundaries of the present invention.

I claim:

1. In a fuel burner apparatus including one or more primary fuelatomizing means, an ignition means and a tubular housing extending fromsaid atomizing means and forming an elongated combustion chamber, theimprovement which comprises;

one or more longitudinal baffle means partially extending into saidcombustion chamber. 2. The invention as set forth in claim 1 whereinsaid tubular housing contains a plurality of said baffle means each ofwhich is convex in shape and are axially aligned about the innerperiphery of said housing, the exterior edges of each of said bafflesdefining, with said periphery, axially aligned slots between the baffleand the housing so as to direct said air through said slots along thecurved wall of said inner periphery inwardly of said combustion chamberforming a plurality of counterrotating vortices.

3. The invention as set forth in claim 1 wherein each of said bafi'lemeans includes means forming a radially oriented extended slot thereinadjacent the end of said bafile means opposite said atomizing means,said slot directing a portion of said air radially across the end ofsaid combustion chamber forming a pneumatic restriction partiallyconfining combustion products within said combustion chamber to insuremore uniform combustion.

4. The invention as set forth in claim 1 in which the baffle meanscomprises a concave baffle plate spaced from the interior wall of saidhousing thereby forming at least a pair of axially aligned slotsadjacent the edges of said plate to direct said air along the curvedwall of said inner periphery outwardly of said slots in oppositedirections forming at least a pair of counterrotating vortices.

5. The invention as set forth in claim 4 wherein the concave wallforming the baffle plate converges with the wall of said housing to forma narrowed slot to accelerate the exiting air therefrom. I

6. A fuel burner apparatus including one or more primary fuel atomizingmeans, an injection means and a tubular housing extending from saidatomizing means forming an elongated combustion chamber comprising;

.. a plurality of longitudinal bafile means convex in shape partiallyextending circumferentially around and spaced from the inner peripheryof the housing, and

means adjacent said baffle means for injecting air between said bafilemeans and the inner periphery of said housing, the exterior edges ofeach of said convex baffles defining with said inner periphery axiallyaligned slots between the baffle and the housing, said air beingdirected through said slots along the curved wall of said innerperiphery inwardly of said combustion chamber in at least two oppositelydirected streams from one of said convex bafiles,

forming a plurality of counterrotating vortices which impinge adjacentthe axis of injection of atomized fuel from said primary fuel atomizingmeans into said combustion chamber.

1. In a fuel burner apparatus including one or more primary fuelatomizing means, an ignition means and a tubular housing extending fromsaid atomizing means and forming an elongated combustion chamber, theimprovement which comprises; one or more longitudinal baffle meanspartially extending circumferentially around and spaced from the innerperiphery of the housing, means adjacent said baffle means for injectingair between said baffle means and the interior periphery of saidhousing, and means to direct said air along the curved wall of saidinner periphery of said housing inwardly into said combustion chamber inat least two oppositely directed streams from one of said partiallyextending baffle means, thereby forming at least a pair of impinginglongitudinally extending, counterrotating vortices adjacent the axis ofinjection of atomized fuel from said primary fuel atomizing means intosaid combustion chamber.
 2. The invention as set forth in claim 1wherein said tubular housing contains a plurality of said baffle meanseach of which is convex in shape and are axially aligned about the innerperiphery of said housing, the exterior edges of each of said bafflesdefining, with said periphery, axially aligned slots between the baffleand the housing so as to direct said air through said slots along thecurved wall of said inner periphery inwardly of said combustion chamberforming a plurality of counterrotating vortices.
 3. The invention as setforth in claim 1 wherein each of said baffle means includes meansforming a radially oriented extended slot therein adjacent the end ofsaid baffle means opposite said atomizing means, said slot directing aportion of said air radially across the end of said combustion chamberforming a pneumatic restriction partially confining combustion productswithin said combustion chamber to insure more uniform combustion.
 4. Theinvention as set forth in claim 1 in which the baffle means comprises aconcave baffle plate spaced from the interior wall of said housingthereby forming at least a pair of axially aligned slots adjacent theedges of said plate to direct said air along the curved wall of saidinner periphery outwardly of said slots in opposite directions formingat least a pair of counterrotating vortices.
 5. The invention as setforth in claim 4 wherein the concave wall forming the baffle plateconverges with the wall of said housing to form a narrowed slot toaccelerate the exiting air therefrom.
 6. A fuel burner apparatusincluding one or more primary fuel atomizing means, an injection meansand a tubular housing extending from said atomizing means forming anelongated combustion chamber comprising; a plurality of longitudinalbaffle means convex in shape partially extending circumferentiallyaround and spaced from the inner periphery of the housing, and meansadjacent said baffle means for injecting air between said baffle meansand the inner periphery of said housing, the exterior edges of each ofsaid convex baffles defining with said inner periphery axially alignedslots between the baffle and the housing, said air being directedthrough said slots along the curved wall of said inner peripheryinwardly of said combustion chamber in at least two oppositely directedstreams from one of said convex baffles, forming a plurality ofcounterrotating vortices which impinge adjacent the axis of injection ofatomized fuel from said primary fuel atomizing means into saidcombustion chamber.